Monomeric siloxanes in conventional polycarbonates are disclosed in DOS 2,920,450. Oligomeric siloxanes in conventional polycarbonates are disclosed in DOS 2,832,342. Cyclic siloxanes in conventional polycarbonates are disclosed in DOS 2,832,339. Vinyl polymers containing silicon epoxide in filled conventional polycarbonates are disclosed in DOS 2,327,014 (LeA 15 025). No improvement in impact strength in the course of long term aging is observed in these products. Glass fiber reinforced polycarbonates with improved mechanical properties obtained by the addition of organopolysiloxanes are disclosed in DE-OS 2 518 287 (Le A 16 254) Polycarbonates corresponding to structural formulae (Ia) are not mentioned there. DE-OS 2,920,451 (Le A 19 567) discloses the use of organic silicon compounds in combination with oxetane compounds, dioxanes or tetrahydrofurans for the stabilization and brightening of polycarbonates. Polycarbonates corresponding to structural formulae (Ia) are again not mentioned there.
Mixtures of polycarbonates with organopolysiloxanes characterized inter alia by improved toughness are disclosed in U.S. Pat. No. 2,999,835. Nothing in the reference appears to suggest the improved resistance to thermally induced degradation which characterize the presently claimed compositions.
Lastly, mixtures of polydiorganosiloxane-polycarbonate block cocondensates with siloxanes and with graft polymers and/or with rubber elastic polymers are disclosed in DE-OS 3 908 038 (Le A 26 235). Such mixtures have improved resistance to petroleum hydrocarbons and good low temperature toughness.